The hydrolysis of proteins to produce food ingredients is well known. For example, U.S. Pat. No. 4,165,391 (Corbett) discusses the use of hydrolysed vegetable proteins (HVP) as flavoring agents for providing meaty flavor and/or flavor intensity to foods. Corbett notes that acid hydrolysis of vegetable proteins is the most important method (as compared with enzymic hydrolysis and alkaline hydrolysis) from the standpoint of food products and that hydrochloric or sulfuric acid is generally used in the hydrolysis.
The use of hydrochloric acid in the hydrolysis of proteins has been implicated in the production of chlorohydrins from residual glycerol in the protein source. J. Velisek et al., "Chlorohydrins in Protein Hydrolysates", Z. Lebensm. Unters. Forsch, Vol. 167, pp. 24-44 (1978). Methods of removing chlorohydrins or preventing their formation are discussed in U.S. Pat. No. 4,759,944 (Fasi et al.). Fasi et al. state that preventing the formation of chlorohydrins is impractical without altering the organoleptic qualities (e.g., taste) of the hydrolysed protein. Likewise, decolorizing with carbon or rectification (i.e., fractional distillation) to remove chlorohydrins are characterized as impractical. Fasi et al. disclose a method for removing chlorohydrins from hydrolysed protein which involves subjecting the hydrolysed protein to steam distillation under reduced pressure while keeping the density of the hydrolysed protein substantially constant.
While the steam distillation method of Fasi et al. may well reduce the concentration of chlorohydrins in a hydrolysed protein, it is difficult to understand how such a method, involving steam distillation under reduced pressure, will not also remove volatile aroma and flavor components from the hydrolysed protein and thereby alter its organoleptic qualities.